That's hard to answer and we never know how they will be once they get off the drugs. The longer they have been using, the more damage they have done to their brains and some heal over time and some never do...brains are delicate that way.
One thing I do know is that as long as she is using, she will become more and more difficult. Addiction is a progressive disease.
If they have children, I would not leave them in her care. She is incapable of being responsible while using pills and the children could be in danger. Even if she has managed so far, the potential for trouble is huge.
I am sorry your son is going through this, it must be hard for you too. I will keep you all in my prayers.
Hugs